Erratum: The Pristine survey – VI. The first three years of medium-resolution follow-up spectroscopy of Pristine EMP star candidates. Issue 4 (23rd December 2019) - Aguado, David S; Youakim, Kris; González Hernández, Jonay I; Prieto, Carlos Allende; Starkenburg, Else; Martin, Nicolas; Bonifacio, Piercarlo; Arentsen, Anke; Caffau, Elisabetta; de Arriba, Luis Peralta; Sestito, Federico; Garcia-Dias, Rafael; et al.